1. Field of the Invention
The present invention relates to a method and apparatus for separating isotopes.
2. Description of the Related Art
As an isotope separation scheme, a scheme using a laser beam is available. In this isotope separation scheme using a laser beam, isotopes are selectively ionized by using a laser beam, and the ionized isotopes are electrically separated from one another.
For example, U.S. Pat. No. 4,035,574 issued to Kurt D. Kennedy discloses such an isotope separation scheme using a laser beam. The principle of this patent or other known isotope separation schemes using a laser beam will be described below. A material containing a plurality of types of isotopes is stored in a material container. This material is continuously irradiated with an electron beam emitted from an electron gun. Upon irradiation with the electron beam, the material is heated to a high temperature. The heated material is melted and evaporated. As a result, vapor flows of the isotopes are continuously produced. Thereafter, a specific isotope to be recovered is irradiated with a selected laser beam. In addition, an ionization laser beam is radiated on the specific isotope to be recovered. The specific isotope irradiated with the ionization laser beam discharges electrons to become an ionized isotope having a positive charge. This vapor flow as the ionized isotope passes through an electric field space formed between an anode and a cathode. When the isotopes pass through the electric field space only the ionized isotope is deflected to a surface of the cathode to be absorbed/recovered. On the other hand, neutral atoms such as the non-ionized isotope passes straight between the two electrodes to be recovered by a vapor recovery plate arranged behind the electrodes.
In such a conventional isotope separation scheme using a laser beam, however, the following problems are posed because a material stored in a material container is irradiated with an electron beam to be melted and evaporated.
The first problem is that the material container for holding a heated/melted material must be cooled due to limitations imposed on a material constituting the container in terms of heat resistance, corrosion resistance, and the like. For this reason, the amount of required electron beam energy is the sum of the energy amount required for melting the material and the energy amount lost in cooling of the material container. The energy amount lost in cooling of the material container is irrelevant to the object of the scheme and hence is equivalent to wasted energy.
The second problem is that part of an electron beam incident on a material surface is reflected thereby and scattered in the apparatus. For this reason, part of the electron beam does not contribute to evaporation of the material. That is, energy is not effectively utilized.
The third problem is that when a material is evaporated by using an electron beam, since a vapor generated by heating collides with the electron beam, the vapor is ionized. The ionized vapor flows between the electrodes. As a result, the ionized vapor is recovered by the effect of the electric field together with specific isotope ions. This degrades the degree of isotope separation.
As described above, in the conventional isotope separation scheme using a laser beam, since an electron beam as a heat source is used to evaporate a material, the loss of energy is large, and recovery of isotopes is adversely affected by electrons, thus posing various problems.